Obstructive Sleep Apnoea (OSA) is a condition characterised by the partial or complete collapse of the upper airway during sleep. OSA comprises a continuous spectrum of severity ranging from simple snoring and upper airway resistance through mild to severe symptomatic obstructive hypopnoea and apnoea. The prevalence of sleep disordered breathing in the adult population is 24% males and 9% for females. The prevalence of symptomatic OSA in the adult population has been estimated to be 4% in males and 2% in females. These patients demonstrate behavioural and neuropsychological consequences to varying degrees, including excessive daytime sleepiness, intellectual deterioration and depression. More serious consequences include arterial systemic hypertension, arterial pulmonary hypertension and heart disease.